Hoechst Aktiengesellschaft

Gunter Jacobsen

Hans Fernholz

Dieter Freudenberger

Dieter Arnold

Gunter Mau

Heinrich Lenzmann

Heinz Wendt

Jorg Bartels

Manfred Stoltenberg

Erich Brandes

In this process for the preparation of ketene by the thermal, catalytic cracking of acetic acid under reduced pressure, the hot cracked gases are cooled to approx. 0.degree. to -10.degree. C. and, in the course thereof, water, unreacted acetic acid and acetic anhydride are condensed. The quantity of acetic acid employed for the thermal cracking reaction should be 0.5 to 2.5 t.times.hours.sup.-1 .times.m.sup.-3, relative to the volume V of a shell-and-tube heat exchanger through which the cracked gas is passed. The pressure drop in the tubular heat exchanger should be 50 to 150 mbars and the surface/volume ratio should be 60 to 120 m.sup.-1.

Process for the preparation of ketene

Ketene is compressed by means of a liquid ring pump using ketene-containing diketene as operating liquid.

Process for compressing ketene

Process for the continuous preparation of hydroxypivalaldehyde by the reaction of isobutyraldehyde with aqueous formaldehyde in a cascade of stirred vessels in the presence of an alcohol and of an alkali metal hydroxide as a catalyst.

Process for the continuous preparation of hydroxypivaldehyde

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Frankfurt-am-Main, Germany

Gunter Jacobsen